Machine for grinding or sharpening edge tools



April 1939- E. G. SCHULZE 2,153,275

MACHINE FOR GRINDING 0R SHARPENING EDGE TOOLS Filed Dec/l4, 1956 2 Sheets-Sheet l April 4, 1939. SCHULZE 2,153,275

MACHINE FOR GRINDING OR SHARPENING EDGE TOOLS Filed Dec. 14, 1936 2 Sheets-Sheet 2 265 a I 110.6. 71 .1 47 A, 7 273 511; 15

is 4O 22 amen om Ernest G. Scivza%@ Patented Apr. 4, 1939 UNITED STATES PATENT OFFICE MACHINE FOR GRINDING OR SHARPENING EDGE TOOLS Ernest G. Schulze, Jersey City, N. J. Application December 14, 1936, Serial No. 115,839

7 Claims. (Cl. 51-80) 1' This invention relates generally to machines longitudinally across and in linear contact with for grinding or sharpening edge-tools; and it has the periphery from the larger-diameter curved to do more particularly with the grinding or portion to the smaller-diameter curved portion sharpening of cutting edges of ordinary knives. to form or provide acomposite cutting edge hav- ,'5 Accordingly, in explaining the principles of the ing portions extending at difierent angles. :5; invention, reference will be made for the sake of The machine embodying this invention coma concrete illustrative example to this particular prises opposed members, one of which comprises use, but it is to be understood that this reference a rotatable or similarly movable peripheral grindis merely illustrative and not restrictive because ing member, said members cooperating to prothe invention is obviously applicable to the grindvide a grinding path or throat substantially: 1Q ing or sharpening of other edge tools having one wedge-shaped or cusp-shaped in cross-section to or more edges to be ground or sharpened. receive and contact an edge tool to be ground, The grinding or sharpening of knives, such as said path varying in cross-section from one end those used by butchers for example, has hereto the other, and means for driving'said grindlll tofore required considerable time and skill and ing member. Most desirably the opposed memit has been difficult, even for a skilled operator, bers comprise a pair of rotary tapered or conic-a1 to properly sharpen a knife without producing a grinding wheels mounted with their peripheries feather edge and without reducing the blade in rolling contact on a .line which forms the more than was required to produce a proper edge, closed bottom of the grinding path or throat and thus unnecessarily shortening the life of the with the smaller-diameter portions thereof ad- 20 knife. Because of these difficulties, it has been jacent each other so that both sides of the knife the practice for butchers and the like to have or other edge tool will be reduced as it is passed their knives sharpened by experts who make a or drawn longitudinally along said pathin conregular business of this, but this not only intact with said grinding wheels.

,25 volves considerable expense but is objectionable -In order further to explain the underlying for other reasons. principles of the invention, a specific practical One of the objects of this invention is to proembodiment of the method, and of a machine vide a machine which will reduce to a minimum for carrying it out, will be shown in the accomthe degree of personal skill required in the grindpanying drawings and described in detail here- 39 ing or sharpening of knives and similar edgeinafter by way of illustrative example only and tools so that persons without any particular skill not as in any way limiting the broad scope of the can properly grind or sharpen knives and the invention. In these drawings, like very conveniently and quickly. Fig. 1 is a top plan view of a machine em- Another object" of the invention is to provide bodying this invention, with the housing cover a simple compact machine at low cost which will plate removed, 35

operate efficiently and automatically to accu- Fig. 2 is a front side elevation thereof, with the rately sharpen a knife or other edge tool in such cover plate in position, a way as to produce a relatively long, tapering, Fig. 3 is a fragmentary view looking toward composite edge without producing a feather edge. the front end of the right-hand grinding wheel 40 With these and other objects in view which, in Fig- 40 together with the novel features and advantages, Fig. 4 is a sectional view on the line 4-4 of will become apparent from the following descrip- Fig. 1, and tion taken in conjunction with the accompany- Figs. 5 and 6 are diagrammatic views showing ing drawings illustrating one practical form of the sharpening or grinding effect produced by machine embodying the invention, the invention the larger and smaller diameter peripheries, re- ,45

comprises the novel method and machine which spectiv-ely, of the grinding wheels. will first be described and explained by means of Referring to the drawings, the novel machine an illustrative example embodying in desirable there shown may be generally described as compractical form the underlying principles involved prising two opposed tapered or conical peripheral and will then be more particularly pointed out prinding members or wheels l0 and II which in the claims. are rotatably mounted in casing or housing l2 Described generally, the'invention comprises so that their peripheries are contiguous or in contacting a side of a knife or similar edge-tool rolling contact, the grinding wheels being suitwith a tapered rotating or similar moving curved ably driven in opposite directions by driving peripheral abrasive surface and drawing the knife means or gearing indicated generally by 13. As to here illustrated, the axes of the grinding wheels are horizontally disposed, but they may be arranged at an angle to the horizontal or vertically if desired.

The specific construction and arrangement of the grinding members or wheels I0 and I I may differ widely within the scope of the broad invention. In the particularly desirable embodiment here illustrated, each grinding wheel or stone is in the form of a truncated cone having a larger diameter portion or end II] or II and a smaller diameter portion or end Ill or II and is formed of any suitable abrasive or grinding material, such as carborundum, for example. The material of which the grinding wheels are made may vary in composition and hardness, as desired, and in the specific embodiment illustrated the smaller or finishing end or peripheral portion l or I I of each grinding wheel is made of a harder composition than the other parts as indicated at Ill and II in Figs. 1 and 4.

Various arrangements for mounting the rotatable grinding wheels Ill and II may be used. In the example illustrated they are mounted on shafts or spindles I4 and I5 rotatably mounted in bearings I6 and I! carried by U-shaped supports or yokes I8 and I9 swingably or pivotally supported on pins or shafts 20 and 2|, respectively, mounted in casing I2. The shafts I4 and I5 are provided with square arbor portions 22 and 23 which fit into axial openings 24 and 25 provided in grinding wheels I0 and II, respectively, the wheels being clamped in place between thrust bearing bushings 26, 26 and washers 21, 2! by screws 28, 28*, respectively. The grinding wheels I0 and II are thus rotatably and swingably supported for movement toward and away from each other and in order to yieldingly hold them together with their peripheries in rolling contact, contractile springs 29 and 30 are connected to casing I2 by screw 3| and tothe upper swingable ends of yokes I8, I9 by screws 32, 33, respectively.

As best shown in Figs. 1 and 2, the grinding wheel shafts I4, I5 and also shafts 20, 2| are arranged at an acute or oblique angle to each other. The contiguous oblique or conical peripheral surfaces or faces of the grinding wheels I0 and II meet on a line 34 which bisects the angle formed between the shafts I4, I5 and forms the closed bottom. of a cusp-shaped or wedge-shaped space 35 formed between the opposed grinding Wheels, said space providing a V-shaped grinding path or throat with concave side walls to receive a knife or other edge tool to be ground or sharpened. The tapered or frusto-conical grinding wheels are mounted with the larger diameter and smaller diameter'portions In I0 respectively, of one wheel contiguous or adjacent the larger diameter and smaller diameter portions Il II' respectively, of the other wheel with the result that the wedge-shaped grinding path or throat 35 formed by the opposed grinding wheel peripheries gradually varies in crosssection from one end to the other. In other words, the grinding throat 35 formed by the larger-diameter portions Ill and I I of the grinding wheels is narrower and forms a more acute angle (see Figs. 2 and 5) than the throat 35 (see Figs. 2 and 6) formed by the smaller-diameter portions IO and II of said grinding wheels. From the foregoing it will be seen that when a knife blade to be sharpenedis drawn longitudinally through the throat 35 and in contact with and across the opposed peripheries of the grinding wheels I 0 and II, the throat portion 35 formed by the larger-diameter portions I0 and II a of said grinding wheels will act to a greater extent but on a smaller angle on the sides of the knife blade than the throat portion 35 formed by the smaller diameter portions I0 and II' of said grinding wheels. This is an important feature of applicants invention because it makes it possible to automatically grind or sharpen a knife or similar edge tool with a com.- posite edge, which edge has a plurality of different angles formed by the different angles of the grinding path or throat.

Means are provided to equalize movement of the grinding wheels I0 and II toward each other and to ensure that they always come together or meet at a predetermined or definite point or line centrally located relative to the casing I2. In the specific example illustrated this equalizing means (see Figs. 1, 3 and. 4) comprises links 36, 31 pivotally connected to the lower swingable ends of yokes I8, I9, respectively and to the slide member 38 which is slidably mounted on the vertically extending rod 39 secured in sockets provided therefor in the casing I2. From the foregoing it will be clear that the yokes I8, I9 and the rotatable grinding wheels l0 and II carried thereby are connected in such a way that swinging movement of one yoke will cause a corresponding swinging movement of the other yoke so that the grinding wheels will always come together or meet at a definite desired point.

The means indicated generally at I3 for driving or rotating the grinding wheels I0 and II in opposite directions may be of any appropriate character, but that here illustrated has certain practical advantages. As best shown in Figs. 1, 3 and 4, 40 indicates a main shaft journaled at its ends in bearings M and 42 provided in the interior of easing or housing I2. One end of shaft 40 extends from one end of the housing and through the projecting lug 43 and is fitted with a square nut or cap 44 which is arranged to provide a connection by which shaft 40 may be driven by an electric motor or other suitable driving means. The specific construction disclosed is particularly arranged to cooperate with and fit into a driving socket or connection provided by many butchers motor-driven chopping machines in common use today, thereby eliminating the need of a separate motor and speed reducer. When using this source of power, a screw 45 mounted on the exterior of casing I2 engages the chopping machine frame-work and acts as a stop or abutment to prevent relative movement or rotation of housing I2. Secured to shaft 40 are two bevel gears 46, 41 which mesh with combination bevel and spur idler gears 48, 49 rotatably mounted on pins or shafts 20, 2| respectively. The spur gear portions of gear wheels 48, 49 mesh with spur gears 50, 5| secured to grinding wheel shafts I4, I5, respectively. It will be seen from the foregoing description that when main shaft 40 is driven counter-clockwise, as viewed from the right in Fig. 1, grinding wheel II] will also be driven counter-clockwise while grinding wheel II will be driven clockwise, as indicated by the arrows in Fig. 2. In view of the fact that gears 48, 49 are mounted on the pins or shafts 29, 2! which form the axes upon which the yokes I8, I 9 swing, the driving connection does not interfere with the desired swinging movement of said yokes. As a matter of fact, due to the planetary arrangement of gears 46, 48 and 41, 49, respectively,

and the fact that gears 48 and 49 are rotatably mounted on oscillatable pins or shafts 20, 2| to which the yokes I8, I 9 are secured, these latter gears tend to force the upper ends of the yokes and the grinding wheels carried thereby together. Thus the grinding wheels are urged together by spring pressure and by the driving means.

The housing or casing II, which is provided with the movable cover plate 12, not only provides a support and housing for the mechanism, but it also provides a receptacle to receive and hold oil or other suitable lubricant for lubricating the gearing etc. A front plate or apron 52 is secured to the front side of housing l2 by screws or other fastening means and. provides a guardfor the grinding wheels Ill and H as well as a pan or receptacle forholding oil or similar lubricant. The grinding wheels are adapted to dip into this oil bath so' that as they rotate they are covered with a film of oil which eliminates any possibility of burning the knife with the grinding wheels.

In operating method of this invention, a knife blade 53 to be ground or sharpened and shown in cross-section in Figs. and 6 is moved longitudinally through the grinding throat 35 in the direction of the arrow 54 in Fig. 1. The sides of the blade are first acted upon by the larger-diameter portions Mi and ll of. the grinding wheels as indicated diagrammatically ini -Fig. 5, the angle between the sides of the throat, formed by the opposed peripheries of the grinding wheels, and consequently the angleformed by the ground faces or sides of the knife blade being comparatively small or acute. If the grinding were continued, this would result in a very thin cutting edge and produce what is known as a feather edge, that is, an edge so thin that it bends over very easily when brought into contact with bone, gristle, or other hard or tough substances. However, by continuing longitudinal movement of the knife blade through the grinding throat, the sides of the knife blade are gradually reduced on a different and wider angle until the other end of the grinding path or throat is reached. This point is shown diagrammatically by Fig. 6 which shows the comparatively wide angle formed by the smaller-diameter portions lo N of the opposed grinding wheels. From the foregoing it will be seen that by merely drawing the knife blade through the varying grinding throat from the narrow angle end to the comparatively wide angle end, the knife blade is automatically provided with a composite cutting edge with faces at many different angles and that there is no danger of producing the objectionable feather edge even by an unskilled operator.

It is to be understood that the invention is not limited to the exact arrangements shown and described and that various modifications in construction and procedure can be made without departing from the spirit and scope of the invention as defined in the claims.

What is claimed is:

1. An edge-tool grinding machine comprising a rotatable grinding wheel provided with a conical periphery, a second rotatable grinding wheel provided with a conical periphery, said grinding wheels being mounted for movement toward and away from each other and arranged with their peripheries in rolling contact on a line to form a grinding path which varies in cross-section from one end to the other to receive and grind an edge tool passed along said path in contact the machine to carry out the with said grinding wheels, and means pressing said grinding wheels into contact with each other.

2. An edge-tool grinding machine comprising a pair of opposed rotatably-mounted tapered grinding wheels, said grinding wheels being mounted with their peripheries in rolling contact on a line to form a wedge-shaped path varying in cross-section from end to end to receive and grind an edge-tool passed along said path in contact with said grinding wheels, resilient means pressing said grinding wheels into contact with each other, and means for rotating said grinding wheels.

3. An edge-tool grinding machine comprising a pair of opposed rotatably-mounted tapered grinding wheels, said grinding wheels being mounted with on a line to form a wedge-shaped path varying in cross-section from end to end to receive and grind an edge-tool passed along said path in contact with said grinding wheels, means urging said grinding wheels toward each other, and means equalizing the movement of said grinding wheels toward each other.

4. A knife sharpening device comprising two pivoted supports movable toward each other, rotatable members each provided with a tapered peripheral abrasive surface and mounted one on each support adjacent a swinging end thereof, said rotatable members being arranged with their peripheries in rolling contact on a line to form a V-shaped path varying in cross-section from end to end to receive and abrade a knife blade passed along said path in contact with said members, and resilient means pressing said sup ports toward each other and said rotatable members together.

5. A knife sharpening device comprising two rotatable shafts disposed at an acute angle relative to each other, two rotatable members each provided with a peripheral abrasive surface arranged at an oblique angle relative to its axis of rotation, said members being mounted, one on each shaft, with their oblique peripheral surfaces in contact to form therebetween a continuous V-shaped throat which varies in cross-section from end to end to receive and abrade a knife blade passed through said throat in contact with said members, and means for urging one shaft toward the other to maintain the rotatable members in contact.

6. An edge-tool grinding machine comprising two supports movable toward each other, pivots for said supports, tapered grinding wheels rotatably mounted one .on each support adjacent a swinging end thereof and with their peripheries in rolling contact on a line to form a wedgeshaped path varying in cross-section from end to end to receive and grind an edge-tool passed along said path in contact with said grinding wheels, gear wheels rotatably mounted one on each support and operatively connected to the grinding wheel mounted on said support to swing therewith, idler gear wheels rotatably mounted one on each pivot, and drive gear wheels for rotating said idler gear wheelsin opposite directions, said idler gear wheels each meshing with a gear wheel carried by a support and so disposed relative thereto that they drive the said gear wheels carried by the supports and simultaneously urge the supports and the grinding wheels carried thereby toward each other.

7. An edge-tool grinding machine comprising a housing, two supports movable toward each their peripheries in rolling contact drive gear wheels for rotating said idler gear wheels in opposite directions, a drive shaft rotatably mounted in said housing and carrying said drive gear wheels, and means for rotating said drive shaft, said idler gear wheels each meshing with a gear wheel carried by a support and so disposed relative thereto that they rotate the said gear wheels carried by the supports and. simultaneously urge the supports and the grinding Wheels carried thereby toward each other.

ERNEST G. SCHULZE. 

